a small change: remove a code which is not very useful
a small change: remove a code which is not very useful

The event dispatched to parent frame is dispatched from window to box
and then back to window, so the old code is not enough to hide it.
Only `preventDefault` can stop the extra event, but it will stop the
page from scrolling, which is not expected.

gdh1995/vimium-plus,gdh1995/vimium-plus,gdh1995/vimium-plus